Patent Application
20190376123
Comparative Genomic Hybridization (CGH) is a method that evaluates genomic content. CGH can be used to analyze congenital abnormalities, inherited diseases and cancers, for example.
We have discovered methods of evaluating genomic content using encoded particles to evaluate multiple samples in parallel. In some embodiments, differences in genomic content can be detected by evaluating DNA from an unknown sample and reference DNA in parallel, e.g., without combining DNA for analysis and reference DNA into a single mixture. The DNA for analysis and reference DNA remain separate from one another. The multiple samples can be evaluated with a single label, for example. In some other embodiments, a single detection label is used to detect differences in genomic content by comparing DNA for analysis and reference DNA in the same mixture. The DNA for analysis and the reference DNA can have different direct or indirect labels, for example. The methods can also be used to evaluate other nucleic acids, e.g., mRNA, as in gene expression analysis.
In one aspect, the disclosure features a method of evaluating genomic DNA. The method uses a mixture that includes particles from different particle sets. Each particle set contains numerous encoded particles and a nucleic acid hybridization probe for a particular genomic locus, such that the mixture collectively includes probes for a plurality of different genomic loci. The method can include: providing a genomic DNA sample and a particle mixture; contacting the sample to a portion of the particle mixture under hybridization conditions; and evaluating hybridization of the sample to particles in the respective portion of the mixture by monitoring a detectable label. Signals from the monitoring are indicative of the number of copies of each interrogated genomic locus.
More than one nucleic acid sample (e.g., a sample including genomic DNA) can be provided. For example, each nucleic acid sample can be evaluated according to the method. The samples can be evaluated in separate compartments. In some embodiments, the more than one DNA samples can be evaluated in the same compartment.
In some embodiments, the detectable label can be detectable by spectroscopy. An exemplary detectable label can contain phycoerythrin or other fluorescent molecule.
In some embodiments, the nucleic acid hybridization probe includes or is derived from cloned nucleic acid. For example, the nucleic acid hybridization probe can contain nucleic acid from a bacterial artificial chromosome (BAC). The BAC nucleic acid can contain a segment of human genomic DNA or non-human (e.g., mouse, rat, rabbit, ginea pig, hamster, goat, cow, dog, cat, horse, bird, reptile, non-human primate (e.g., monkey or baboon), or fly) genomic DNA.
In some embodiments, the nucleic acid hybridization probe can contain one or more oligonucleotides (e.g., a collection of oligonucleotides) specific for a particular chromosomal locus. For example the probes can be specific for sequences that are within 50, 20, 5, 2, 1, or 0.5 megabases of one another.
In some embodiments, at least 2, 5, 10, 20, 50, 100, or 200 different particle sets can be used, e.g., to evaluate a respective number of different genomic loci. In some embodiments, all the encoded particles of a particle set can have the same code. In other embodiments, each particle has a unique code, and information is stored indicating which particles are in which particle sets or which probes are attached to each particle.
In some embodiments, at least one sample of the plurality can be a reference sample, with a known number of copies for each interrogated genomic locus. The method can include comparing signals from monitoring the reference sample to signals from other samples to determine the number of copies of each interrogated genomic locus for the samples.
In some embodiments, where more than one DNA sample is provided, each sample can be labeled with a first indirect label, and each sample can be combined with reference DNA labeled with a second indirect label. The reference DNA can be genomic DNA from a reference source with a known number of copies for each interrogated genomic locus. For example, the first indirect label can be fluorescein and the second indirect label can be biotin.
In some embodiments, the evaluating can involve (i) binding, to a first portion of the sample, a first moiety that includes the single label and an agent that binds the first indirect label, and (ii) binding, to a second portion of the sample, a second moiety that includes the single label and an agent that binds the second indirect label. For example, the first moiety can include streptavidin or avidin and a detectable label (e.g., phycoerythrin), and the second moiety can include an anti-fluorescein antibody or functional portion thereof and a detectable label (e.g., phycoerythrin). In some embodiments, at least 5, 10, 20, 30, 50, 70, or 100 particles from each of the different particle sets for each genomic sample are evaluated.
Where more than one sample is provided, each of the more than one samples can be in a different compartment of a multi-compartment device. In some embodiments, each sample can be in a different well of a multi-well plate. The multi-well plate can be a 96-well, 384-well, or 1024-well assay plate.
The method can be used, e.g., to detect heterozygosity at a plurality of different chromosomal loci, chromosomal amplification can be detectable, loss of heterozygosity, a heterozygous deletion of a chromosomal locus, or a homozygous deletion of a chromosomal locus.
In some embodiments, the particles are not contacted with a polymerase, e.g., after the hybridization. In some embodiments, the particles are not contacted with any enzyme, e.g., after the hybridization.
In some embodiments, the genomic DNA samples can be unlabeled. The method can further include hybridizing labeled probes to the genomic samples, wherein, for each of the nucleic acid hybridization probe attached to particles, a labeled probe hybridizes to a genetically linked site at the same genomic locus, such that if the genomic locus is present in the sample, the labeled probe can be immobilized to the particle by a complex formed by hybridization of the labeled probe to a sample nucleic acid strand and hybridization of the sample nucleic acid strand to the nucleic acid hybridization probe attached to the particle. In some embodiments, the labeled probes can be hybridized concurrently with hybridizing the genomic DNA samples to the nucleic acid probes attached to the particles. In some embodiments, the labeled probes can be hybridized subsequent to hybridizing the genomic DNA samples to the nucleic acid probes attached to the particles.
In some embodiments, the method can further include labeling genomic DNA from a source with an indirect label to provide a genomic DNA sample.
In some embodiments, for example where a single detectable label is used, the method can further include the step of labeling genomic DNA from a source with the single label to provide a genomic DNA sample. In some embodiments of the method, all of the genomic DNA samples can be labeled with the single label.
In some embodiments, all of the genomic DNA samples having unknown genomic content can be labeled with the same indirect label. In some embodiments, a majority of the genomic DNA samples can be labeled with the same indirect label.
In some embodiments, the method can further include agitating the particles prior to evaluating hybridization.
For example, the particles can be holographically encoded or encoded with fluorescent dyes that have spectra separable from that of the single detected label. In some embodiments of the method, the particles can be have magnetic properties. For example, the particles are paramagnetic beads.
In another aspect, the disclosure provides a method of evaluating genomic DNA using a single detectable moiety and a particle mixture, the mixture including particles from different particle sets, wherein each particle set contains numerous encoded particles and a nucleic acid hybridization probe for a particular genomic locus, such that the mixture collectively includes probes for a plurality of different genomic loci. The method includes: providing at least one reference DNA sample and a plurality of genomic DNA samples. Each sample is labeled with the same detectable moiety. The method also includes: contacting each of the samples to a portion of the particle mixture under hybridization conditions; and evaluating hybridization of each sample to particles in the respective portion of the mixture by monitoring the detectable moiety. For example, each sample is contacted to the particle mixture in a separate vessel. The signals from the monitoring can be indicative of the number of copies of each interrogated genomic locus. The method can include other features described herein.
In another aspect, the disclosure features a method of evaluating nucleic acid using a single detectable label and a particle mixture, the mixture including particles from different particle sets, wherein each particle set contains numerous encoded particles and a nucleic acid hybridization probe for a particular target, such that the mixture collectively includes probes for a plurality of different target. The method can include: providing at least one reference nucleic acid sample that is labeled with a first indirect label and a plurality of test nucleic acid samples. Each test sample is labeled with a second indirect label. The method can include: contacting each of the test samples and the reference sample to a portion of the particle mixture under hybridization conditions, wherein each test sample is contacted to the particle mixture and the reference sample in a separate vessel; binding, to a first portion of each test sample, a first moiety that includes the single label and an agent that binds the first indirect label; binding, to a second portion of each test sample, a second moiety that includes the single label and an agent that binds the second indirect label; evaluating each test sample by monitoring the single label in the first portion of the sample and the single label in the second portion of the sample. The signals from the monitoring can be indicative of the number of copies of each target. The method can include, for each test sample, comparing signals from the single label in the first portion to signals from the single label in the second portion, to obtain an indication of the number of copies of a probe in the test sample relative to the reference sample. The method can include other features described herein.
In another aspect, the disclosure provides a particle mixture, which mixture contains particles from different particle sets, wherein each particle set can contain numerous encoded particles and a nucleic acid hybridization probe for a particular genomic locus, such that the mixture collectively includes probes for a plurality of different genomic loci.
In some embodiments, the probe for at least some of the loci can contain bacterial artificial chromosome DNA. In some embodiments, the probe for at least some of the loci can contain sonicated bacterial artificial chromosome DNA. In some embodiments, the probe for at least some of the loci can contain a collection of synthetic oligonucleotides.
In some embodiments, the particle mixture can further include particles including hybridized DNA from at least two samples, wherein each sample includes genomic DNA and each sample can be labeled with a different indirect label. In some embodiments, the particle mixture can further include hybridized DNA from a single sample that is labeled with a detectable label, or hybridized DNA from more than a single sample (e.g., a first sample and a second sample).
In another aspect, the disclosure features a multi-compartment plate having a multiple compartments, where each of at least a plurality of the wells can contain: a particle mixture such as any of those described herein; and a sample or reference genomic nucleic acid. The sample and the reference nucleic acid can be in separate vessels. In some embodiment, the sample and reference nucleic acid can be detectable with the same label.
In another aspect, the disclosure feature a kit that includes: a reference genomic DNA (or other reference nucleic acid) sample labeled with a first indirect label; reagents for labeling genomic DNA (or other nucleic acid) samples with a second indirect label. The kit can also include one or more of: a first moiety that includes the single label and an agent that binds the first indirect label; a second moiety that includes the single label and an agent that binds the second indirect label; and a particle mixture such as any of those described herein. The kit can also include, optionally, instructions for how to detect the single label and/or for performing an assay using the kit.
Also disclosed is a kit that includes one or more of the components described herein. The kit can further include materials that includes instructions for using the components for a method, e.g., a method described herein. The kit can include one or more cloned or synthesized nucleic acid sequences (such as bacterial artificial chromosomes (BACS) or one or more collections of synthetic oligonucleotides, or individual oligonucleotides), one or more microwell plates, and/or one or more sets of particles, e.g., as described herein, or a mixture of particles.
Particles, such as beads, provide a particularly robust system for evaluating genomic content. Particle-base methods include hybridization close to or at solution phase kinetics, therefore providing enhanced uniformity. Particles facilitate obtaining many data points for a particular probe. For example, for small particles (e.g., particles up to several microns in diameter) at least 10, 50, or 100 particles having the same probe can be individually analyzed. Large particles can enable obtaining multiple data points from discreet locations on each particle. For large particles, often fewer particles are needed to obtain many data points. Statistics can be applied to determine the median or average signal for the population of particles with the same probe content.
The methods described herein can be used for ratiometric assays. The ratiometric approach corrects for many potential errors in the accuracy of the assay by performing multiple assays competitively and simultaneously. Any variations in incubation conditions or the concentrations of the capture molecules or label reagents, for example, are corrected by normalization. Competitive and non-competitive ratiometric assays can be used, e.g., for comparative genomic content or gene expression.
All patents, patent applications, and references cited herein are hereby incorporated by reference.
Multiplex nucleic acid assays are greatly facilitated by efficient and economical design features. As described herein, single-label detection can be used to perform large multiplex assays. The assays utilizes a mixture of small particles from different particle sets. Each particle set contains numerous encoded particles and a nucleic acid hybridization probe for a particular target, such as a particular genomic locus or RNA. Particles from different sets can be combined to provide a mixture that collectively includes probes for a plurality of different targets.
In one example, the particle mixture is divided into at least two portions, A and B. The test sample genomic DNA is labeled with a first moiety and hybridized to the labeled A portion. The reference DNA (typically genomic DNA from a reference sample) is labeled with a moiety that can be the same as the first moiety or different (i.e., a second moiety). The reference DNA is hybridized to the B portion. The signals from the A portion and the B portion are measured and then compared. If the reference DNA and the sample DNA are labeled with the same moiety, they are processed in different vessels. With little manipulation, both hybridization reactions can be evaluated using a device configured to detect the moiety if it is a direct label or is coupled to a direct label (e.g., before or after hybridization).
The moieties that are used can be an indirect label (such as a dye used as an indirect label), a direct label (such as dye, e.g. a fluorophore), or a member of a specific binding pair. Detection can be direct or indirect, e.g., by secondary detection by using a labeled second member of the specific binding pair.
In a second example, the test and reference sample genomic DNA are labeled, each with a different indirect label. The indirect label is typically a first member of a specific binding pair. The samples are mixed with each other and hybridized to the same portion of a particle mixture. After incubation and washing, the portion is separated into at least two vessels for incubation with the corresponding second members of the two specific binding pairs. These second members of the two specific binding pairs can be coupled to a third label, and if needed a fourth label, which is used for detection. Generally, the detector label and the two indirect labels are all distinguishable from one another. For example, if one or more of the labels are fluorescent labels, they have different excitation and/or emission spectra so that they can be distinguished by spectroscopy.
To illustrate, biotin can be used as the indirect label for the test sample and carboxyfluorescein as the indirect label for the reference sample. Thus, in the first vessel, fluorescently labeled streptavidin (which binds to the biotin) is added and incubated, and in the second, fluorescently labeled anti-fluorescein (which binds to the carboxyfluorescein) is added and incubated. For the LUMINEX xMAP™ system the preferred fluorescent label for detection is phycoerythrin. Each of the incubated particle mixtures with bound fluorescently labeled products (from the test and reference sample) are then read sequentially by using a single-color detection system and the signals compared.
Both these examples illustrate methods for using a single detection to obtain comparative or ratiometric information. In an exemplary application, numerous different patient samples can be processed in a single multiwell plate using a mixture of particles with probes for different targets, e.g., different genomic loci. The particle mixture is placed in each well of the plate. Each sample is put in one of the wells. In this fashion, multiple samples can be processed in parallel and with robotic aids. Then each sample can be evaluated using an instrument (such as a flow cytometer) in order to detect hybridization to the different particle types in the mixture.
In some embodiments, the test and reference samples are labeled with two different direct or indirect labels. If the labels are direct (e.g., fluorescent dyes such as cyanine 3 and cyanine 5), then the samples may be mixed and hybridized to a particle set and detected with an instrument capable of discriminating the two labels. If the labels are indirect (i.e., a first member of a specific binding pair such as biotin and fluorescein) then each second member of a specific binding pair (e.g., streptavidin and anti-fluorescein) can be labeled with a unique detector label such as cyanine 3 and cyanine 5, and detected with an instrument capable of discriminating the two labels.
A variety of different types of particles can be used to evaluate nucleic acid content, e.g., genomic content. The particles can be of any shape (e.g., cylindrical, spherical, and so forth), size, composition, or physiochemical characteristics. The particle size or composition can be chosen so that the particle can be separated from fluid, e.g., on a filter with a particular pore size or by some other physical property, e.g., a magnetic property.
The particles are generally suitable for multiplex assays. For example, each particle includes a unique code, particularly, a code other than the nucleic acid probe specific for genomic DNA. The code is embedded (for example, within the interior of the particle) or otherwise attached to the particle in a manner that is stable through hybridization and analysis. The code can be provided by any detectable means, such as by holographic encoding, by a fluorescence property, color, shape, size, light emission, quantum dot emission and the like to identify particle and thus the capture probes immobilized thereto. In some embodiments, the code is other than one provided by a nucleic acid.
For example, the particles may be encoded using optical, chemical, physical, or electronic tags. Examples of such coding technologies are optical bar codes fluorescent dyes, or other means.
One exemplary platform utilizes mixtures of fluorescent dyes impregnated into polymer particles as the means to identify each member of a particle set to which a specific capture probe has been immobilized. Another exemplary platform uses holographic barcodes to identify cylindrical glass particles. For example, Chandler et al. (U.S. Pat. No. 5,981,180) describes a particle-based system in which different particle types are encoded by mixtures of various proportions of two or more fluorescent dyes impregnated into polymer particles. Soini (U.S. Pat. No. 5,028,545) describes a particle-based multiplexed assay system that employs time-resolved fluorescence for particle identification. Fulwyler (U.S. Pat. No. 4,499,052) describes an exemplary method for using particle distinguished by color and/or size. US 2004-0179267, 2004-0132205, 2004-0130786, 2004-0130761, 2004-0126875, 2004-0125424, and 2004-0075907 describe exemplary particles encoded by holographic barcodes.
U.S. Pat. No. 6,916,661 describes polymeric microparticles that are associated with nanoparticles that have dyes that provide a code for the particles. The polymeric microparticles can have a diameter of less than one millimeter, e.g., a size ranging from about 0.1 to about 1,000 micrometers in diameter, e.g., 3-25 μm or about 6-12 μm. The nanoparticles can have, e.g., a diameter from about 1 nanometer (nm) to about 100,000 nm in diameter, e.g., about 10-1,000 nm or 200-500 nm.
A particle mixture for examining multiple genomic loci can be prepared by combining particles from different particle sets. Each particle set can contain numerous particles with the same code and nucleic acid probe content specific for the particular locus. For example, the number of different particle elements can be in the range of 10-3000, 10-500, 20-200, 50-2000, 50-500, or 50-200, or 75-300. Each particle set can be prepared individually, then a portion of the particle set is combined with portions of other particle sets to provide a particle mixture.
Each portion of a particle set includes numerous particles such that when a portion of the particle mixture is used for analyzing a DNA sample, a number of particles specific for a particular locus (for example, at least 10, 20, 30, 50, 80, or 100 particles; or even 1-5) are present in the hybridization reaction for that individual sample. The particles can be agitated in suspension within a liquid sample to facilitate relatively rapid binding to the probes.
Particles are analyzed to determine the extent of hybridization to the particles. For example, a label associated with the genomic DNA is detected. The particles can be individually evaluated using a device that can read the particle code and determine signals associated with each particular particle.
The particles generally have probes specific to one particular chromosomal locus or gene, depending on the application. For example, probes can be prepared from cloned DNA (for example, BAC or Yeast Artificial Chromosome or other source cloned DNA), amplified DNA, or oligonucleotides. Generally, any source of nucleic acid of determinable sequence can be used. The probes are immobilized to the particles, e.g., on the surface or for porous particles or to internal and/or external surfaces.
One chromosomal probe comprises a mixture of synthesized oligonucleotides. Another exemplary type of chromosomal probe is derived from BAC cloned DNA which can be immobilized as fragmented BAC DNA.
Generally, the probes that can be attached for a particular particle can be a mixture of fragments. For example, the fragments comprise randomly overlapping sequences, the majority of which have lengths between 600 and 2,000 base pairs. A mixture of synthetic oligonucleotide sequences, each of which having a length between about 60 and 150 base pairs, with either overlapping or contiguous sequences, can be prepared as a probe. Oligonucleotide mixture have a deterministic composition and can be prepared in a cost efficient manner.
The probes can be covalently attached to a particular particle. For example, U.S. Pat. No. 6,048,695 describes an exemplary method for attaching probes. If the probe for a particular particle set is one or more chemically synthesized oligonucleotides, the oligonucleotides can be synthesized with a chemical group (e.g., an amine) which can react with groups on the particle. The probe can also be derived from other sources, e.g., plasmids, cosmids, and artificial chromosomes. For example, a bacterial artificial chromosome (BAC) can be sonicated then reacted with a crosslinker that covalently attaches them to the particles. For example, 1-Ethyl-3-[3-dimethylaminopropyl]carbodiimide hydrochloride (EDC or EDAC chemistry) can be used to attach nucleic acid probes, such as sonicated BAC DNA to particles.
Generally, when attaching probes to a particle set, all the particles in the set have the same “code.” Thus, a detector would associate the signals for hybridization to the particular attached probes with the “code” for all the particles in the set. However, it is also possible to use two or more “codes” for the same particular probe. Software (or even manual computation) can be used to then associate signals for the two “codes” with the particular probe. In the extreme, each particle has a unique serial number, i.e., its own code. So long as a database tracks which particle codes are modified with a particular probe, data from the detector can be used to associate signals with hybridization to the probe.
Sample Labeling.
a variety of methods can be use to label the sample dna, e.g., the genomic DNA for analysis. Labels can be introduced by polymerization using nucleotides that include at least some modified nucleotides, e.g., biotin, digoxygenin, fluorescein, or cyanine modified nucleotides. In some embodiments, the label is introduced by random-priming and polymerization. Other examples include nick translation (Roche Applied Science, Indianapolis Ind.; Invitrogen, Carlsbad Calif.) and chemical labeling (Kreatech ULS, Amsterdam NL). Generally, any labeling method appropriate for labeling genomic DNA samples can be used.
Shared Reference.
In many embodiments, the methods evaluate the ratio of the signals between a known reference sample and an unknown experimental sample. For instance, two indirect labels (biotin and fluorescein) are used to allow competitive hybridization of two samples. After hybridization, the sample is divided into two (or more) portion and each portion is evaluated separately. Results from the evaluation can be used to provide the ratio of the two indirect label levels. This approach has the advantage of using the competitive hybridization to normalize any variation between assays: both of the reference and experimental samples are assayed simultaneously in the same vessel mixed with the same particles.
Parallel Reference.
It is also possible for some embodiments to keep the known and unknown samples separate. Competitive hybridization is not used. In this case the reference sample is assayed in one vessel and at least one experimental sample is assayed in another vessel. For example, the vessels can be different wells of a multi-well plate. If multiple experimental samples are used, each can be evaluated in a different vessel, for example a different well of a multi-well plate. The ratio(s) of the experimental sample signals to the reference sample signals for each probe can be obtained in the same way as in the competitive assay.
When this approach is utilized, a single reference sample can be shared between several or many experimental samples. For experiments involving multiple samples per day there can be a savings on reagent cost and labor by avoiding the labeling of multiple duplicate normal samples. Also it is unnecessary to manipulate the sample to obtain different portions for separate analysis. Each sample can be evaluated only once.
Non-Covalently Attached Labels.
In yet another embodiment, the covalent labeling of each sample individually is avoided. For example, unlabeled genomic DNA samples are hybridized to the capture probes immobilized to the encoded particles, wherein said capture probes comprise BAC DNA or oligonucleotide mixtures as described above. Pre-labeled reporter sequences are also hybridized to the probe-sample complexes at sequences adjacent to but not overlapping the sequences of the capture probes. These labeled reporter sequences can be hybridized in the same or in a different hybridization reaction. In this manner the labeled reporter sequences can be manufactured in bulk in a larger-scale environment, lowering the cost per assay compared to individually labeling each sample at the time of the assay.
Signals that are indicative of the extent of hybridization can be detected, for each particle, by evaluating signal from one or more detectable labels. Particles are typically evaluated individually. For example, the particles can be passed through a flow cytometer. Exemplary flow cytometers include the Coulter Elite-ESP flow cytometer, or FACScan™ flow cytometer available from Beckman Coulter, Inc. (Fullerton Calif.) and the MOFLO™ flow cytometer available from Cytomation, Inc., Fort Collins, Colo. In addition to flow cytometry, a centrifuge may be used as the instrument to separate and classify the microparticles. A suitable system is that described in U.S. Pat. No. 5,926,387. In addition to flow cytometry and centrifugation, a free-flow electrophoresis apparatus may be used as the instrument to separate and classify the microparticles. A suitable system is that described in U.S. Pat. No. 4,310,408. The particles may also be placed on a surface and scanned or imaged.
The methods of genomic evaluation described herein have a variety of applications, including diagnostics and forensics. For example, they can be used to determine the genomic content of an adult, a germ cell, a placental cell, or a fetal cell. The cell can be from any species, but is typically from a diploid species or a species with greater ploidy. For example, the cell can be from a plant (e.g., a crop plant) or animal (e.g., a human or domesticated animal).
With respect to human medical use, the methods can be used to evaluate a sample from a patient, e.g., a sample from a biopsy, a blood sample, an amniotic fluid sample, or a cheek swab. In particular, the patient can be a patient at risk for or having a cancer. The sample can be a sample from a tissue that is near a tumor or from a tumor. For example, the methods can be used to evaluate the genomic content of cells from a carcinoma or sarcoma or from a tumor of the lung, breast, thyroid, lymphoid, gastrointestinal, genito-urinary tract, an adenocarcinomas, e.g., a malignancy of colon cancer, renal-cell carcinoma, prostate cancer and/or testicular tumors, non-small cell carcinoma of the lung, cancer of the small intestine and cancer of the esophagus. Many chromosomal loci that are altered in cancer are known. See e.g. Dutrillaux et al. Cancer Genet. Cytogenet. 49:203-217 (1990), U.S. Pat. No. 5,670,314 (lung carcinomas), U.S. Pat. No. 5,635,351 (gliomas), and U.S. Pat. No. 6,110,673. The method can be used to evaluate the genomic content of a blood cell, e.g., a B or T cell, or a cell from a leukemia or lymphoma.
The methods described herein can also be adapted for other nucleic acids, e.g., DNA other than genomic DNA, mRNA, or other RNAs.
Some aspects of the inventions are further illustrated by the following non-limiting examples.
In this exemplary ratiometric assay, particles are used to evaluate on multiple samples in parallel with a single label. For example, different samples are places in separate vessels, such as two separate microplate wells. One or more control reagents are used in each vessels to normalize the results between the two.
An exemplary multi-binding assay using a single label readout system is described as follows. A multiplex multi-binding particle assay is performed with two samples I and II, for example. The assay can be extended to additional samples. Each sample is labeled with an indirect label, such as biotin on sample I and dinitrophenol (DNP) on sample II. The specific analytes from both samples compete for bind to the nucleic acid probes on each particle type. After incubation and washing, the particle set is divided into two vessels for separate incubation with two specific secondary labels. In the first vessel fluorescently labeled streptavidin is added and incubated, and, in the second, fluorescently labeled anti-DNP is added and incubated. For the LUMINEX xMAP™ system, a preferred fluorescent label is phycoerythrin. Particles in each of the incubated particles sets with bound fluorescently labeled products I and II are evaluated sequentially by the single-color detection system that associates particle code with phycoerythrin signal.
Referring to
In
In
In
In
A fluorescently labeled specific complement to each of the indirect labels is then added separately to each aliquot. In this example, streptavidin-phycoerythrin 29 is incubated 31 to the first indirect bead aliquot 27, where the streptavidin specifically binds to the biotin indirect labels on the bead complexes. Separately, anti DNP-phycoerythrin 30 is incubated 32 with the second bead aliquot 28, where the anti DNP specifically binds to the DNP indirect labels on the bead complexes. Next, and still keeping the two aliquots separate, excess fluorescent conjugate is washed away 31 and 32 with wash buffer 35 and 36, Finally, each fluorescently labeled bead aliquot is read 33 separately, using a LUMINEX xMAP 100™ or xMAP 200™ instrument in this example.
BAC Probes, Standards, and Samples.
Bacteria artificial chromosome (BAC) DNA was used to make immobilized capture probes on encoded beads. Five different human BACs, all supplied by the Health Research Division, Roswell Park Cancer Institute (Buffalo, N.Y.), were used as immobilized capture probes in the following experiments: RP11-289D12 (15q11.2); RP11-524F11 (17p11.2); RP11-1398P2 (4p16.3); RP11-476-C20 (22q11.21); RP5-59D14 (17p13.3). These BACs are listed by Roswell Park clone # with the chromosomal locus in parentheses.
These BACs were used as standards in the experiments. A pool of the five BACs was used to make enzymatically labeled positive samples using Klenow random-primer labeling with biotin-labeled and unlabeled nucleotides. Additionally, Cot-1 DNA (Invitrogen 15279-011, Carlsbad Calif.) was immobilized to encoded beads as a negative control.
BAC probe preparation and immobilization onto beads. BAC DNA was immobilized on LUMINEX xMAP™ beads from Luminex (Austin Tex.). xMAP™ beads are made of polystyrene functionalized with carboxyl groups on the surface. These beads are offered in both para-magnetic and non-magnetic versions. The paramagnetic beads facilitate separating the beads from solution for wash steps, but the same protocol works for non-magnetic beads where washes are performed on filter columns or plates (e.g. HTS 0.45 μm, catalog MSHVN4510, Millipore, Billerica Mass.).
The BAC and control probe immobilization protocol onto magnetic LUMINEX beads was as follows.
For a demonstration assay, sample DNA was prepared by pooling the same BAC DNA fragments that were used to prepare the multiplex bead. The BAC DNA, being double-stranded, will hybridize specifically with themselves after denaturing, allowing standard curves to be generated with samples of known concentration. Dilutions of at each of eight concentrations, in two-fold dilutions down from 6.25 ng/ml, were used as standards. Each of these DNA dilutions was divided into two aliquots, and each of the two aliquots labeled with either fluorescein or biotin to create indirectly-labeled samples.
Labeling was done using a standard BioPrime™ BAC planar microarray random primer labeling kit (Invitrogen, Carlsbad Calif.) substituting biotin-labeled and fluorescein-labeled nucleotides for the standard cyanine dye labeled nucleotides. Details are as follows:
The above protocol was repeated with fluorescein nucleotides replacing the biotin nucleotides in a second fluorescein master mix at Step 4. The products of these two operations were: a biotin labeled BAC pool and a fluorescein labeled BAC pool. These comprised labeled pools of the same BACs used as probes, which would be perfect-match positive hybridization complements to the immobilized probes. The same procedures can be used for sample of nucleic acid prepared from a cell, e.g., genomic DNA from a patient or other subject.
Eight pairs of the indirectly labeled samples were then each hybridized to the LUMINEX multiplexed bead set, the eight pairs being made up of increasing concentrations of fluorescein-labeled sample mixed with decreasing concentrations of biotin-labeled sample, per the notations along the horizontal axis of the plot in
As detailed above in steps (7-9), after the two-sample competitive hybridization assays using the indirect labels were completed, the multiplex assayed bead sets were divided again. One aliquot was secondarily labeled with 4 μg/ml anti-fluorescein-phycoerythrin and the other with 4 μg/ml streptavidin-phycoerythrin. Each of these secondarily labeled bead sets was then read separately on a LUMINEX xMAP 200™ system.
The results are shown in
In a exemplary assay that illustrates another aspect of the invention, synthetic 70-mer amine-modified oligonucleotide probes (Operon Biotechnologies, Huntsville Ala.) were immobilized to the Luminex multiplex beads and a single-color assay was performed where the reference and test samples were not in the same well. This experiment utilized 17 different probes, four of which were pooled or combined sets of five oligonucleotides representing loci on the X and Y chromosomes as detailed in the table below. With this multiplex probe set a demonstration assay that differentiates male and female DNA was performed.
The protocol for coupling the amine-modified oligonucleotide probes to the encoded Luminex xMap microspheres or beads to make the multiplex oligo bead mix was as follows.
Assuming 100% recovery, the resulting oligo-coupled bead concentration is ˜12,500 microspheres/μL.
Standard normal genomic DNA, pooled from a number of nominally normal individuals of the same sex (Promega, Madison Wis.) was used as the test samples in this assay. Male DNA was used as the test sample and female DNA for the reference. Labeling 2 μg of each sample was performed with the Invitrogen BioPrime kit and Spectral Genomics reagents as in Example 4 above, except that biotin nucleotides were substituted for the cyanine nucleotides in the kit to yield biotin-labeled samples.
The multiplex demonstration assay was performed on the Luminex xMAP beads with both samples in duplicate, utilizing four wells in a 96-well microplate per the protocol below.
The results of the demonstration assay are shown in
Multiplex differential gene expression is commonly performed on printed microarrays using a two-fluorophore assay. In this type of assay two RNA samples, a reference and a sample to be tested, are enzymatically converted to cDNA by reverse transcriptase in the presence of labeled nucleotides. The cDNA products thus have a fraction of their nucleotides fluorescently labeled whereby they can be detected optically. Each sample is labeled separately with two different fluorophores, typically cyanine 3 and cyanine 5, and the labeled samples are pooled and competitively hybridized to a microarray. The ratio of the two dyes at each element of the microarray, detected on a fluorescence scanning instrument, is thus indicative of the relative concentration of each assayed RNA sequence in its respective sample.
This type of assay was performed on paramagnetic Luminex xMAP™ beads with a single fluorophore readout according to an aspect of the present technology. Oligonucleotide (“oligo”) probes representing 38 genes were obtained from Operon (Huntsville Ala.). These oligo probes were of 70-mer length with an amine group at the terminal 5′ end. Each oligo sequence was immobilized onto a set of xMAP beads with a particular xMAP bead ID code or region, using the common EDAC coupling chemistry. The 38 genes represented were NRP2, CARD14, IGFALS, TSSC3, PSEN2, IGFBP4, TP53BP2, GAPD, PRODH, TNFRSF7, RAB6KIFL, ILF1, BCL2L2, DNASE1L3, PPP1R15A, PIG11, HSPD1, CDH1, IGFBP5, IRF1, TNFRSF10C, TNFRSF17, LTA, DFFB, IL16, PTPN13, IL3, TNFSF18, CCNG1, CCND1, TUCAN, RIPK3, CASP6, IL2, TNFAIP2, IL24, K-ALPHA-1, and TRIP, along with a negative control. The 39 bead types were then pooled into a multiplex bead set, and aliquots from this set were placed into the wells of a 96-well microplate to perform a gene expression assay as described below.
For the purpose of demonstrating the technology, a single reference RNA sample was used (Universal Human Reference RNA, Stratagene, La Jolla Calif.). The single sample was split into two, and the expected result of a differential assay is thus a ratio of 1:1 for each gene. This is a common evaluation performed on gene expression platforms. According to an aspect of the present technology, one aliquot of RNA was labeled with biotin and the other with fluorescein as indirect labels. These two indirectly labeled samples were then pooled and mixed with the multiplex bead sets prepared previously and allowed to hybridize simultaneously.
After hybridization the assayed bead set was divided into two aliquots. Streptavidin-phycoerythrin reporter reagent (specific to the biotin-labeled sample) was added to an incubated with one aliquot, and anti-fluorescein-phycoerythrin (specific to the fluorescein-labeled sample) was added to and incubated with the other. Phycoerythrin is the preferred reporter fluorophore in the xMAP™ instrument. The paramagnetic bead aliquots were then pulled to the microplate well walls by a plate magnet, the liquid reagent withdrawn by a pipette, and the labeled beads were resuspended in a wash buffer. The two aliquots of beads were then read sequentially on a Luminex xMAP 200™ instrument.
The resulting signal data were plotted on a scatter plot, as shown in
Other embodiments are within the scope of the claims.
This application claims priority to U.S. Application Ser. No. 60/753,584, filed on Dec. 23, 2005, U.S. Application Ser. No. 60/753,822, filed on Dec. 23, 2005, U.S. Application Ser. No. 60/765,311, filed on Feb. 3, 2006, and U.S. Application Ser. No. 60/765,355, filed on Feb. 3, 2006, the contents of each of which are hereby incorporated by reference.
| Number | Date | Country | |
|---|---|---|---|
| 60765311 | Feb 2006 | US | |
| 60765355 | Feb 2006 | US | |
| 60753584 | Dec 2005 | US | |
| 60753822 | Dec 2005 | US |
| Number | Date | Country | |
|---|---|---|---|
| Parent | 11615739 | Dec 2006 | US |
| Child | 16236599 | US |
